Autographs and other signed items can fetch a higher than normal price if they are accompanied by documents which certify the authenticity and the time and date or setting of the autograph. A photograph of the event will help improve the authenticity of an autograph.
Collectibles such as stamps, coins, comic books, action figures and trading cards can be evaluated and graded by a third party. The condition of the items is granted a score based on standardized criteria. Graded collectibles tend to achieve higher sales prices than non-graded items in similar condition.
Rarity and Availability
Low availability coupled with high demand can be a winning formula when it comes to pricing. The harder it is to get, the more someone will pay for it, even if the item will eventually be made available on a larger scale. Early adopters of video game systems and smart phones have been shown to pay unusually high prices just to have the item before anyone else.
Limited edition items and numbered editions can be very desirable to collectors, particularly if the manufacturing or print run can be quantified.
Antiques and collectibles are that much more likely to attract a collector's attention if the seller can detail the historical significance of an item. Maker's marks, signatures with dates, provenance (the history of ownership for an item) and details related to design, creation or history of an item can increase value.